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Evolutionary consequences of ecological interactions
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Eco-evolutionary dynamics integrates the reciprocal interactions betweenecology and evolution. These two branches of biology traditionally assumethe other as static for simplicity. However, increasing evidence shows thatthis simplification may not always hold because ecology and evolution canoperate in similar timescales. This thesis theoretically explores how thereciprocal interactions may influence ecological and evolutionary outcomesin four different eco-evolutionary contexts.Many species of non-social animals live in groups. Aggregating ingroups often has both benefits and costs that depend on group size. Thanksto the benefits of aggregation, population growth likely depends positivelyon population density when it is small. This phenomenon, the Allee effect,has been hypothesized to explain the evolution of aggregation behavior. Ifind that the Allee effect alone does not lead to the evolution whenpopulation dynamics is explicitly accounted for. Some other mechanisms,such as frequent needs for colonizing new patches or anti-aggregation,should be invoked to explain why aggregation behavior could evolve.Phenotypic plasticity is the ability of a genotype to express distinctphenotypes when exposed to different environments. Although it is oftenshown to be adaptive and not costly, highly plastic organisms are rare. Paststudies demonstrated some potential reasons. I test another possibility; costsmay arise from sexual selection because highly plastic individuals may beless preferred as a mate. I show that, even in the absence of the direct cost ofplasticity, the level of plasticity remained low at intermediate strengths ofassortative mating. This pattern is robust across wide ranges of parametervalues.Ecological speciation occurs when ecologically divergent selectionbetween environments causes reproductive isolation between divergingsubpopulations. Several verbal models of ecological speciation emphasizethe roles of phenotypic plasticity in promoting speciation. The complexprocesses involved in speciation, however, are difficult to be evaluated byverbal accounts. I quantitatively test the proposed idea in a mechanisticmodel of ecological speciation in the presence and absence of plasticity. Ifind conditions under which plasticity can promote or hinder ecologicalspeciation. Plasticity facilitates speciation by producing a gap in thedistributions of expressed phenotypes, which serves as a barrier to gene flowin an assortatively mating population.Ecosystem ecology and evolutionary biology are the least integratedfields in ecology and evolution. Natural selection operating at the individuallevels on traits governing ecosystem functions may affect ecosystemproperties, which may feedback to individuals. I reviewed this idea anddemonstrate the feedback loop by using a simple consumer-resource model.

Place, publisher, year, edition, pages
Umeå: Umeå universitet , 2014. , 24 p.
Keyword [en]
adaptive dynamics, eco-evolutionary dynamics, ecological speciation, ecosystem, individual based, population dynamics, phenotypic plasticity, predator-prey, sexual selection
National Category
Ecology
Identifiers
URN: urn:nbn:se:umu:diva-87734ISBN: 978-91-7601-018-1 (print)OAI: oai:DiVA.org:umu-87734DiVA: diva2:710674
Public defence
2014-04-29, Naturvetarhuset, N200, Umeå universitet, Umeå, 10:00 (English)
Opponent
Supervisors
Available from: 2014-04-08 Created: 2014-04-07 Last updated: 2014-04-08Bibliographically approved
List of papers
1. Evolutionary suicide as a consequence of runaway selection for greater aggregation tendency
Open this publication in new window or tab >>Evolutionary suicide as a consequence of runaway selection for greater aggregation tendency
2013 (English)In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 317, 96-104 p.Article in journal (Refereed) Published
Abstract [en]

Aggregation of individuals is a common phenomenon in nature. By aggregating, individuals can reap benefits but may also be subject to associated costs from increased competition. The benefits of aggregation can depend on population density, which in turn can be affected by aggregation when it determines reproductive success of individuals. The Allee effect is often considered to be one of the factors that can explain the evolution of aggregation behavior. We investigated this hypothesis with a mathematical model which integrates population dynamics and evolution. Individuals gain synergistically from aggregation but suffer from scramble competition with aggregation tendency as an evolving trait. We found that aggregation behavior can stabilize the population dynamics and reduce population growth. The results show that the Allee effect alone is not sufficient for aggregative behavior to evolve as an evolutionarily stable strategy. We also found that weak local competition does not promote aggregation due to feedback from the population level: under low competition, the population can achieve high density such that aggregation becomes costly rather than beneficial. Our model instead exhibits an escalation of aggregation tendency, leading to the extinction of the population in a process known as evolutionary suicide. We conclude that for aggregation to evolve as an evolutionarily stable strategy we need to consider other factors such as inter-patch dispersal to new patches and avoidance of excessively large groups. 

Place, publisher, year, edition, pages
Elsevier, 2013
Keyword
Invasion fitness, Adaptive dynamics, Allee effect, Site-based model
National Category
Biological Sciences
Identifiers
urn:nbn:se:umu:diva-66650 (URN)10.1016/j.jtbi.2012.09.033 (DOI)000313758500011 ()
Available from: 2013-03-05 Created: 2013-02-26 Last updated: 2017-12-06Bibliographically approved
2. Assortative mating can limit the evolution of phenotypic plasticity
Open this publication in new window or tab >>Assortative mating can limit the evolution of phenotypic plasticity
2014 (English)In: Evolutionary Ecology, ISSN 0269-7653, E-ISSN 1573-8477, Vol. 28, no 6, 1057-1074 p.Article in journal (Refereed) Published
Abstract [en]

Phenotypic plasticity, the ability to adjust phenotype to the exposed environment, isoften advantageous for organisms in heterogeneous environments. Although the degrees ofplasticity appear limited in nature, many studies have reported low costs of plasticity invarious species. Existing studies argue for ecological, genetic, or physiological costs orselection eliminating plasticity with high costs, but have not considered costs arising fromsexual selection. Here, we show that sexual selection caused by mate choice can impede theevolution of phenotypic plasticity in a trait used for mate choice. Plasticity can remain low tomoderate even in the absence of physiological or genetic costs, when individualsphenotypically adapted to contrasting environments through plasticity can mate with eachother and choose mates based on phenotypic similarity. Because the non-choosy sex (i.e.,males) with lower degrees of plasticity are more favored in matings by the choosy sex (i.e.,females) adapted to different environments, directional selection toward higher degrees ofplasticity is constrained by sexual selection. This occurs at intermediate strengths of femalechoosiness we tested. Our results demonstrate that mate choice is a potential source of anindirect cost to phenotypic plasticity.

Place, publisher, year, edition, pages
Springer, 2014
Keyword
assortative mating, disruptive selection, magic trait, mate choice, phenotypic diversification, phenotypic plasticity, sexual selection, individual-based model
National Category
Ecology Evolutionary Biology Other Mathematics
Identifiers
urn:nbn:se:umu:diva-87674 (URN)10.1007/s10682-014-9728-5 (DOI)000344075200006 ()
Available from: 2014-04-07 Created: 2014-04-07 Last updated: 2017-12-05Bibliographically approved
3. Mechanisms by which phenotypic plasticity affects adaptive divergence and ecological speciation
Open this publication in new window or tab >>Mechanisms by which phenotypic plasticity affects adaptive divergence and ecological speciation
Show others...
2015 (English)In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 186, no 5, E126-E143 p.Article in journal (Refereed) Published
Abstract [en]

Phenotypic plasticity is the ability of one genotype to produce different phenotypes depending on environmental conditions. Several conceptual models emphasize the role of plasticity in promoting reproductive isolation and, ultimately, speciation in populations that forage on two or more resources. These models predict that plasticity plays a critical role in the early stages of speciation, prior to genetic divergence, by facilitating fast phenotypic divergence. The ability to plastically express alternative phenotypes may, however, interfere with the early phase of the formation of reproductive barriers, especially in the absence of geographic barriers. Here, we quantitatively investigate mechanisms under which plasticity can influence progress toward adaptive genetic diversification and ecological speciation. We use a stochastic, individual-based model of a predator-prey system incorporating sexual reproduction and mate choice in the predator. Our results show that evolving plasticity promotes the evolution of reproductive isolation under diversifying environments when individuals are able to correctly select a more profitable habitat with respect to their phenotypes (i.e., adaptive habitat choice) and to assortatively mate with relatively similar phenotypes. On the other hand, plasticity facilitates the evolution of plastic generalists when individuals have a limited capacity for adaptive habitat choice. We conclude that plasticity can accelerate the evolution of a reproductive barrier toward adaptive diversification and ecological speciation through enhanced phenotypic differentiation between diverging phenotypes.

Place, publisher, year, edition, pages
University of Chicago Press, 2015
Keyword
assortative mating, eco-evolutionary dynamics, ecological, speciation, habitat choice, individual-based model, phenotypic plasticity
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-87677 (URN)10.1086/683231 (DOI)000363928900003 ()
Note

Originally published in thesis in manuscript form.

Available from: 2014-04-07 Created: 2014-04-07 Last updated: 2017-12-05Bibliographically approved
4. Toward an integration of evolutionary biology and ecosystem science
Open this publication in new window or tab >>Toward an integration of evolutionary biology and ecosystem science
Show others...
2011 (English)In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 14, no 7, 690-701 p.Article in journal (Refereed) Published
Abstract [en]

At present, the disciplines of evolutionary biology and ecosystem science are weakly integrated. As a result, wehave a poor understanding of how the ecological and evolutionary processes that create, maintain, and changebiological diversity affect the flux of energy and materials in global biogeochemical cycles. The goal of thisarticle was to review several research fields at the interfaces between ecosystem science, community ecologyand evolutionary biology, and suggest new ways to integrate evolutionary biology and ecosystem science.In particular, we focus on how phenotypic evolution by natural selection can influence ecosystem functionsby affecting processes at the environmental, population and community scale of ecosystem organization.We develop an eco-evolutionary model to illustrate linkages between evolutionary change (e.g. phenotypicevolution of producer), ecological interactions (e.g. consumer grazing) and ecosystem processes (e.g. nutrientcycling). We conclude by proposing experiments to test the ecosystem consequences of evolutionary changes.

Place, publisher, year, edition, pages
John Wiley & Sons, 2011
Keyword
biodiversity and ecosystem functioning, community genetics, eco-evolutionary dynamics, ecological stoichiometry, ecosystem science, evolutionary biology, feedbacks, natural selection
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-87678 (URN)10.1111/j.1461-0248.2011.01627.x (DOI)000292865200008 ()
Available from: 2014-04-07 Created: 2014-04-07 Last updated: 2017-12-05Bibliographically approved

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Nonaka, Etsuko

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